That kind of adapter would work to let you play any region on any region. The only lockout on the SNES is physical shape. USA carts are too fat, and JPN/Euro systems are too tight for them to fit. Skinny JPN/Euro carts could fit in baggy USA systems, but NOA added small tabs to specifically block them.
The adapter is the same slim shape as the JPN/Euro carts, and it slips past the lockout tabs, so it should fit in anything. The pins are just a passthrough extension. And then the top opening is roomy and makes no attempt to block anything. It looks nice inside your SNES/SFC.
Unfortunately, it also lifts your carts up high and makes no attempt to support them. Picture for a moment, taking one of your favorite games and setting it up on your coffee table, letting go, and watching it fall over backward or forward. Now picture, the only thing stopping that is a bunch of tiny little hands that are grabbing your cart by it's PCB. If the hands break, or the PCB breaks, the cart falls over. Okay, that probably won't happen, but it feels unsettling just looking at it. I buried mine in the closet several hours after I bought it.
The easiest region-free mod is breaking the tabs out of an American SNES. Modding an SFC or Euro SNES is harder, and usually not pretty.